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[SelectionDAG] Fix another place that was passing a large value to APInt::lshrInPlace. 

llvm-svn: 300821
This commit is contained in:
Craig Topper 2017-04-20 04:55:01 +00:00
parent ed004ef206
commit 9ce5ef9475
1 changed files with 16 additions and 14 deletions
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30
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -1205,21 +1205,23 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
getShiftAmountTy(Op.getValueType(), DL));
}
APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
OperandBitWidth - BitWidth);
HighBits.lshrInPlace(ShAmt->getZExtValue());
HighBits = HighBits.trunc(BitWidth);
if (ShAmt->getZExtValue() < BitWidth) {
APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
OperandBitWidth - BitWidth);
HighBits.lshrInPlace(ShAmt->getZExtValue());
HighBits = HighBits.trunc(BitWidth);
if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) {
// None of the shifted in bits are needed. Add a truncate of the
// shift input, then shift it.
SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl,
Op.getValueType(),
In.getOperand(0));
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl,
Op.getValueType(),
NewTrunc,
Shift));
if (!(HighBits & NewMask)) {
// None of the shifted in bits are needed. Add a truncate of the
// shift input, then shift it.
SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl,
Op.getValueType(),
In.getOperand(0));
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl,
Op.getValueType(),
NewTrunc,
Shift));
}
}
break;
}